A few years ago (c. 2009), some folks in Berkley, CA developed a program to promote energy improvements on real property through a local government funded loan program that provides for repayment through an increase in property tax assessments over up to a 20 year period. The program is called PACE (Property Assessed Clean Energy and several states have passed legislation to encourage implementation.
In 2010, Fannie Mae and Freddie Mac "poo-pooed" the idea because potential default might place mortgage lenders further down the list for financial recovery in the event of default.
The idea still has traction. My thinking is that power brokers are very cool to such decentralization and that is exactly where our Federal Government and politicians become obstacles in the way of a potentially huge paradigm shift embracing conservation and efficiency.
Imagine how many small "Mom & Pop" smal contractors might be suddenly flush with new work if such a program could gain a significant foothold.